Represent RegUnit liveness with LiveRange instance

Previously LiveInterval has been used, but having a spill weight and
register number is unnecessary for a register unit.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@192397 91177308-0d34-0410-b5e6-96231b3b80d8

lib/CodeGen/InterferenceCache.h

@@ -72,7 +72,7 @@ class InterferenceCache {
       unsigned VirtTag;
 
       /// Fixed interference in RegUnit.
-      LiveInterval *Fixed;
+      LiveRange *Fixed;
 
       /// Iterator pointing into the fixed RegUnit interference.
       LiveInterval::iterator FixedI;